To me, the idea behind Extreme Programming can be summed up as follows: What would happen if we take what we know works, and do it to degree that seems at first unreasonable?
You will quickly notice that testing will be more effective if you test earlier. What is unreasonably early: Testing before we have something to test. Thus the idea of test-driven development is born.
You will quickly notice that code review is an effective form of improving quality and spreading knowledge in the team. What is an unreasonable amount of code review: All code should be written by two people. That is, pair programming.
Similarly, the idea of user stories comes from the observation that communication between users and developers is key to effective development of a user friendly system.
Some of the ideas of extreme programming don’t feel so extreme anymore. But the spirit should live on. What would it mean to do what we know works today to an unreasonable degree?
Take continuous integration for example. Most teams use continuous integration to run tests when they check in the code. What would happen if we ran the tests whenever something changes? Most languages support continuous testing or autotesting today and teams are starting to adopt this now.
Frequent releases may mean once every 1-3 months for many organizations today. What would happen if you increased the frequency from months to weeks, or from weeks to days. Or from days to hours? Some extreme organizations actually push changes into production automatically when their batteries of automated tests succeed.
Short iterations work and reducing parallel work helps many organizations today. What if we got away from the iteration altogether, and a developers pick the next story when ready. What if we delayed all discussions about the user story until a developer was ready to start programming it? Many organizations are working with variations of kanban to increased flow and reduce waste.
Extreme Programming means pushing the things that work further than we’ve done before. What good ideas would you like to do to an unreasonable amount?